The present invention relates generally to fuel equalizing systems and methods for equalizing the fuel in a plurality of fuel tanks mounted on motor vehicles such as trucks in order to maintain substantially the same amount of fuel in each tank. The fuel equalizing system and method of the present invention employs an equalization valve which senses the pressure in the fuel outlet of each fuel tank and controls the return flow of unused fuel from the motor to such tanks in order to equalize the amount of fuel in the tanks. The equalization valve includes a valve actuator member having at least two pressure sensing elements on such actuator member which sense the pressure at the outlets of two fuel tanks and cause the actuator member to move longitudinally to operate the valve in accordance with the tank pressure. A pair of valve elements are provided at the opposite ends of the actuator member to control the flow of unused return fuel flowing from the motor through two return fuel outlets of the valve back into the two fuel tanks. The valve elements are moved by the actuator member to control the return fuel flow by varying the spacing between each valve element and its associated stop.
The fuel equalization system of the present invention is especially useful for diesel engines on trucks in order to equalize the amount of fuel in two or more fuel tanks on such trucks, but is also useful for other motor vehicles including boats and airplanes.
It has previously been proposed in U.S. Pat. No. 2,860,651 of Davies, issued Nov. 18, 1958 and U.S. Pat. No. 2,860,652 of Badger, issued Nov. 18, 1958, to provide an apparatus for controlling the emptying of two fuel tanks on an airplane including a control valve having two pressure sensing chambers which sense the pressure within the two fuel tanks to operate a valve actuator which has its opposite ends connected to flexible diaphragms in such chambers. Each of the two separate sensing chambers is divided by a diaphragm into two separate sealed chambers, one of which is connected to the tank air pressure above the fuel in the tank and the other of which is connected to the fuel pressure within the tank. The two tanks in the fuel system of the Badger patent are interconnected by a modulating valve also having a flexible diaphragm therein and having an outlet connection to the pressure actuator control valve. The fuel equalizing valve of the present invention differs from that of the above cited patents by fuel pressure sensors not employing flexible diaphragms which are subject to wear, but rather employing spherical ball sensor elements on a valve actuator member to sense the pressure difference at the fuel outlets of the two fuel tanks. This moves the actuator member and two valve elements on such actuator member to control the return flow of unused fuel from the motor though valve into such tanks to equalize the amount of fuel in the tanks. The equalizing valve of the present invention is therefore much simpler, less expensive and more trouble-free in operation than that of the prior fuel equalizing system of such patents.
U.S. Pat. No. 4,722,358 of Christensen, dated Feb. 2, 1988, shows a pressure equalizing spool valve including a pair of sliding cylindrical valve elements at the opposite ends of a connecting rod which move in accordance with the pressure difference between a pair of pressure sensing ports in the opposite ends of the valve casing in communication with the bore passage of such sliding valves. Unlike the present invention, the valve is not provided with spherical sensing balls attached to the actuator member for sensing the pressure difference between the outlets of two fuel tanks and does not control the return flow of unused fuel from the motor to the fuel tanks in the manner of the present invention. U.S. Pat. No. 2,483,312 of Clay issued Sep. 27, 1949 shows a hydraulic pressure spool valve including a sliding valve actuator and a pair of pistons, the opposite ends of which engage two loose spherical valve elements. In their closed position the spherical valve elements engage valve seats to close the valve passages, but are urged against adjustable stops at the opposite ends of the valve in the open position of such valve elements. However, unlike the equalizer valve of the present invention, there are no spherical sensing elements attached to a valve actuator member for moving such actuator member and valve elements at the opposite ends thereof to change the spacing between such valve elements and adjustable stops in order to control the return flow of unused fuel from the motor to the fuel tanks in the manner of the present invention.